Forty Ross 308 hybrid broiler chickens at the age of 20 days were included in the study. They were raised under the same conditions in the vivarium of the FVM at LTU - Sofia in bird cages with 10 chicks per cage. Twenty of the chickens (experimental group) received Lavandula angustifolia Mill essential oil in the daily feed ration at a final concentration of 0.01% or an average of 5 mg per chicken, from the 20th day to the 42th day of age. Pooled faecal samples were taken from all birds in both groups on the first day, on the 15th day after their arrival (in the middle of the experimental period) and at the end of the experiment. Microbiological studies of the samples were carried out, as for the isolation of microorganisms cultures were made in elective and selective nutrient media for bacteria from different groups, as well as for fungi, and their identification was carried out biochemically with the help of polymicrotests. Intake of lavender essential oil with food resulted in a more than two-fold reduction in the number of bacterial species in their faeces from major groups including pathogenic species as well as Candida ovale fungi. These data show that lavender oil exerts a significant antimicrobial effect in vivo, as a result of which their feces contain significantly less microorganisms with pathogenic potential and, accordingly, they are much louer dangerous from an epizootological point of view than those of normally fed birds.
Mladenova et al. (Sun,) studied this question.